   (:import (java.math BigDecimal MathContext RoundingMode)))
 
 (defn nonzero?
-  "Is x non-nil and non-zero?"
-  [x]
-  (and x (not= 0 x)))
+  "Is v non-nil and non-zero?"
+  [v]
+  (and v (not= 0 v)))
 
 (defn divide-some
   "Zero-safe division (returns value or nil)"

  "Return the arithmetic mean of vs, or nil if empty"
  [vs]
  (when (seq vs)
    (/ (apply + vs) (count vs))))

(defn median
  "Return the median value of vs, or nil if empty"

    (/ n div)))

(defn ^BigDecimal bigdecimal
  "Convert v to a java.math.BigDecimal, representing ratios as doubles"
  [v]
  (if (ratio? v)
    (bigdec (double v))
    (bigdec v)))

(defn ^BigDecimal round-bigdecimal
  "Round BigDecimal `v` to specified number of significant digits"
